Interleukin (IL)-13 is a 114 amino acid cytokine with an unmodified molecular mass of approximately 12 kDa (McKenzie, A. N., et al. J Immunol, 1993. 150:5436-44; Minty, A., et al. Nature, 1993. 362:248-50). IL-13 levels have been shown to correlate with disease severity in asthmatics and rodent models of allergic inflammation (see U.S. Pat. Appl. Publ. No. 2012-0052060, published Mar. 1, 2012, and incorporated herein by reference in its entirety).
Bronchial asthma is a common persistent inflammatory disease of the lung characterized by airways hyper-responsiveness, mucus overproduction, fibrosis, and raised serum IgE levels. Airways hyper-responsiveness (AHR) is the exaggerated constriction of the airways to non-specific stimuli such as cold air. Both AHR and mucus overproduction are thought to be responsible for the variable airway obstruction that leads to the shortness of breath characteristic of asthma attacks (exacerbations) and which is responsible for the mortality associated with this disease.
Current British Thoracic Society (BTS) and Global Initiative for Asthma (GINA) guidelines suggest a stepwise approach to the treatment of asthma (Society, B. T., Thorax, 2003. 58 Suppl 1:1-94; GINA, Global Strategy for Asthma Management and Prevention. 2002, National Institute of Health). Mild to moderate asthma can usually be controlled by the use of inhaled corticosteroids, in combination with beta-agonists or leukotriene inhibitors. However, due to the documented side effects of corticosteroids, patients tend not to comply with the treatment regime, which reduces the effectiveness of treatment (Milgrom, H. et al. Ann Allergy Asthma Immunol, 2002. 88:429-31; Fish, L. and C. L. Lung, Ann Allergy Asthma Immunol, 2001. 86:24-30; Bender, B. G. J Allergy Clin Immunol, 2002. 109: S554-9).
Chronic Obstructive Pulmonary Disease (COPD) includes patient populations with varying degrees of chronic bronchitis, small airway disease, and emphysema, and is characterized by progressive irreversible lung function decline that responds poorly to current asthma based therapy. Zheng et al (J Clin Invest, 2000. 106:1081-93) have demonstrated that overexpression of IL-13 in the mouse lung caused emphysema, elevated mucus production, and inflammation, reflecting aspects of human COPD. The signs are therefore that IL-13 plays an important role in the pathogenesis of COPD, particularly in patients with asthma-like features. IL-13 may also play a role in the pathogenesis of inflammatory bowel disease, and has been associated with fibrotic conditions, such as idiopathic pulmonary fibrosis (IPF). See, e.g., Jovani, M., et al. Curr Drug Targets. 2013.12:1444-52; and Rafii, R., et al. J Thorac Dis. 2013. 1:48-73
Periostin (also known as Osteoblast-Specific Factor 2) is a matricellular protein belonging to the fasciclin family (Masuoka, M., et al. J Clin Invest 2012. 122:2590-2600). Periostin is a highly inducible product of IL-4 or IL-13 in lung fibroblasts, and is involved in fibrosis of bronchial asthma, and other firms of allergic inflammation (Id.). While increased periostin levels are known to correlate with certain IL-13-mediated diseases or disorders, there remains a need for specific and sensitive assays to determine changes in periostin levels in patients suspected or known to have an IL-13-mediated disease or disorder.